Surface polishing apparatus and method therefor

ABSTRACT

An apparatus and method utilizing a polishing slurry for fine polishing of articles as lenses or the like, in the operation of which the slurry, with its abrasive or polishing particles suspended therein, is initially confined under pressure against the article surface to be polished and then subjected to vibratory movement which causes polishing movement of the slurry polishing particles over this article surface and thus uniform polishing thereof.

United States Patent 2] Inventor Hans S. Hirschhorn 30 Brook Path, Plainview, N.Y. 11803 1211 Appl. No. 826,382 [22] Filed May 21, 1969 [45] Patented June 29, 1971 [54] SURFACE POLISHING APPARATUS AND METHOD THEREFOR 6 Claims, 3 Drawing Figs.

[52] U.S.C1 51/7, 51/284,51/317 [51] Int. Cl B241) 19/00 [50] Field ofSearch 51/7, 17, 59, 284, 317, 318, 283, 281

[56] References Cited UNITED STATES PATENTS 2,554,701 5/1951 Hackett 51/7 2,664,675 1/1954 La Monica 51/7 Primary ExaminerWilliam R. Armstrong Attorney-Jerome Bauer ABSTRACT: An apparatus and method utilizing a polishing slurry for fine polishing of articles as lenses or the like, in the operation of which the slurry, with its abrasive or polishing particles suspended therein, is initially confined under pressure against the article surface to be polished and then subjected to vibratory movement which causes polishing movement of the slurry polishing particles over this article surface and thus uniform polishing thereof.

PATENTEU JUNZSIQYI 3589-1071 l I k 22 INVENTOR fzy. 7 HANS s. HIRSCHHORN M/AU ATTORNEY SURFACE POLISHING APPARATUS AND METHOD THEREFOR The present invention relates generally to ultrasonic polishing techniques, and more particularly to improvements in zip paratus and method utilizing ultrasonic vibration and a polishing slurry for fine polishing of articles as lenses and other accurately generated surfaces.

It is already well known, according to US. Pat. No. 3,154,890 issued to .l. H. Lemelson and similar patents, how to achieve a polishing function utilizing vibration and a polishing slurry. Generally, the polishing slurry, which contains abrasive or polishing particles, is flowed into contact with and thus against and progressively along the surface to be polished and consequently causes polishing thereof. To intensify this polishing action, which otherwise would be too time consuming to be commercially practicable, ultrasonic vibrators or transducers are used to cause vibration in the flowing slurry and have been found to effectively accelerate the polishing. The adap tion of the foregoing for fine polishing of articles, as lenses or other accurately generated ophthalmic surfaces, is not entirely satisfactory, however, since uniform polishing is not always achieved. Specifically, it is believed that the area of the surface against which the slurry initially impinges is subjected to a more vigorous polishing action than other areas, and that this contributes to nonuniform polishing. Another contributing factor is the existence of air bubbles in the flowing slurry which, in an obvious manner, interferes with the polishing action of the slurry and results in the production of aberrations in the finished surface.

Broadly, it is an object of the present invention to provide an improved surface polishing apparatus and method overcoming the foregoing and other shortcomings of the prior art. Specifically, it is an object to provide a vibratory apparatus utilizing a polishing slurry in the mode of operation of which the slurry has an effective polishing action.

A surface polishing apparatus demonstrating objects and advantages of the present invention includes means defining a polishing chamber about a surface to be polished and means for admitting and nonflowingly confining under pressure, a polishing slurry in such chamber to thereby establish void free contact against the surface. Thereafter, vibratory devices such as transducers, are operated to cause impingement of the abrasive or polishing particles of the slurry against the surface which results in polishing thereof. By avoiding flow of the slurry during the polishing operation and relaying on void free pressurized impingement, it has been found that effective, uniform polishing results.

The above brief description, as well as further objects, features and advantages of the present invention, will be more fully appreciated by reference to the following detailed description of a presently preferred, but nonetheless illustrative embodiment in accordance with the present invention, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of a surface polishing apparatus in accordance with the present invention;

FIG. 2 is a plan view illustrating additional structural features thereof; and

FIG. 3 is a side elevational view, in section taken on line 3-3 of FIG. 2, illustrating internal structural features thereof.

Reference is now made to the drawings wherein there is shown a surface polishing apparatus, generally designated 10, demonstrating objects and advantages of the present invention. Apparatus includes two major components. The first is a housing structure generally identified 12 which, as best shown in FIG. 3, defines an internal chamber 14. The second is a pressure applying device or cylinder generally identified by numeral 16 effective to apply pressure to a fluid medium which is caused to flow, preparatory to operation of the surface polishing apparatus 10, from the pressure applying device 16 into the chamber 14. MOre specifically, the referred to medium will be understood to be a conventional polishing slurry consisting ofa fluid body and abrasive or polishing particles suspended in such body, the fluid body and said particles being individually and collectively designated 18.

As generally understood, the polishing slurry I8 is a material well known for its polishing action: during movement relative to a surface to be polished. Also, as is generally well understood, the referred to polishing function is limited to the smoothing and, as in the case of ophthalmic media, the creat' ing of transparency in a lens surface or the like article which has previously been produced by a fine grinding or other such operation. Thus, the polishing slurry 18 heretofore and in the present application is not intended to nor is it used to generate the lens or a similar surface but rather only to produce a fine polishing thereof. As will be explained in greater detail herein, apparatus 10 is effective in achieving this fine polishing of lenses or other such accurately produced surfaces in a uniform manner and without causing undesirable excessive reduction in any localized area of the surface.

Turning now more specifically to the construction of the apparatus 10, in a preferred form as illustrated, the housing structure 12 includes a generally cylindrical upstanding wall 20, a bottom wall 22 and a top opening 24 of a size which accommodates, in a snug or force fit, a cover member 26 having an annular sealing ring 28 rendering the chamber 14 fluid tight. Cover member 26 has a central counterbore 30 which accommodates a holding member 32 which, in turn, is appropriately attached either adhesively or by suction to an article such as a lens 34 whose surface is to be fine polished. An elastomeric member 36 is advantageously placed between the article, here shown as a lens 34 and the cover 26 to absorb an excessive vibrational shock as may be transmitted during operation of the apparatus 10. After the lens 34 is positioned and supported in the manner illustrated in which it, in effect, constitutes the upper wall bounding the chamber 14, inadvertent removal of the cover 26 is prevented by dropping down the hinged holding elements 38 spaced circumferentially and located about an upper lip formed about the cylindrical wall 20.

Located opposite the lens 34, in its operative position as just described and in a slightly elevated position from the bottom wall 22, is a housing including an upper wall 42 in which there is appropriately operatively arranged plural transducers, individually and collectively designated 44. As is generally understood, the transducers 44, in response to electrical energization, are effective in producing vibrations in a range and at a frequency which could be ultrasonic.

The pressure applying device 16 includes an outer housing 46 conveniently shown to be formed as a cylinder for a piston 48 which, in response to pressure fluid injected in any well known manner into an upper chamber 50, has a lower piston head 52 which forces the polishing slurry 18 through a port 54 into the space or chamber 14 adjacent the lens surface 35. Specifically, the extent of pressure applied by the piston 48 is such that the polishing slurry I8 completely fills the chamber 14 such that the upper surface of the slurry, in response to the applied pressure, is forced into intimate overall full surface contact with and against the downwardly facing adjacent surface 35 of lens 34 it being understood that this is the surface requiring fine polishing. It has been found that by confining the slurry under pressure within the space defining the chamber 14 adjacent the surface 35, the slurry is nonflowing and in pressurized void free contact with the surface. Thus, the pressurized slurry 18 is free of any air bubbles or other voids throughout its contact with the lens surface 35. The presence of bubbles or voids results in uneven polishing. The void free contact between the slurry and lens surface obviates unequal polishing and undesired aberrations. The result is a A full, even and uniform fine polishing of the lens surface 35. Completing the construction of the pressure applying device 16 is a feed tube 58 for supplying and/or increasing the volume of the bubble free polishing slurry 18 and also a plug 60 for draining the apparatus 10.

After attaining the condition of the apparatus as depicted in FIG. 3, it is contemplated that the polishing operation will be commenced with the electrical energization of the transducers 44. The ultrasonic vibrations of the transducers are transmitted directly to the confined slurry toward which the same are directed and whose polishing particles are pressurized into voidless contact with the lens surface. in response to this vibratory motion, the abrasive or polishing particles of the slurry come into direct physical abrading contact with the lens surface 35 and produce a fine, even and uniform polishing of this surface.

This is in contrast to the prior art use of a polishing slurry which is caused to flow against and along a surface to be polished and relies on this relative movement of the abrasive portion of the slurry to achieve the necessary polishing function. In accordance with the present invention, the polishing slurry 18 does not flow dynamically relative to the lens surface 35 but the vibratory motion induced in such slurry has nevertheless been found to be effective in causing the abrasive particles suspended in the polishing slurry 18 to impinge upon and thereby cause even and uniform polishing of the lens surface 35.

Thus the present invention discloses a unique apparatus and method of fine polishing the surface of an article. Although the apparatus here shown has been disclosed for use in connection with a concavely shaped lens surface of simple or compound contour, the invention is not to be so limited. It will be recognized that the surface 35 could be convex, of a simple or compound contour, or it could be flat or substantially planar. Thus the arrangement of structure of the apparatus may need to be varied in simple details in order to enable its use and operation with articles whose shapes differ from that of the article 34 here enclosed. It is to be recognized, therefore, that the apparatus shown and the article 34 treated in this disclosure, are merely for illustrative and explanatory purposes only.

lt is to be understood that an apparatus having different structural details may be utilized provided the same supports the article whose surface is to be polished in such manner that the surface is exposed adjacent to a space within which the polishing slurry is confined and with which it is in a nonflowing, void free contact, whereby the slurry is able to be placed under pressure to assure the even, uniform, fine polishing of the surface.

A latitude of modification, change and substitution is in tended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features.

What l claim is:

1. An apparatus for polishing a surface of an article comprising I a substantially closed chamber,

means in said chamber to support an article in fixed position in said chamber exposing the surface of the article to be polished,

a polishing slurry in said chamber, said slurry completely filling said chamber and being confined in nonflowing relation with the defines of said chamber and in polishing contact with the fixed surface to be polished, means connected with said chamber to place the polishing slurry therein under pressure to cause the polishing slurry to contact the fixed surface void free and under pressure, and means for vibrating the polishing slurry in said chamber to move the same relative to said fixed surface. 2. A surface polishing apparatus as defined in claim 1 wherein said vibrating means are transducers located at least opposite said surface to be polished and with said polishing slurry therebetween to induce ultrasonic vibrations to said polishing slurry. 3. A polishing apparatus for polishing the surface of an article comprising a polishing chamber including means therein to support the article with the surface thereof to be polished fixedly exposed in said chamber a polishing slurry including polishing particles completely filling and confined in and in nonflowing relation with said chamber and in contact against said surface to be polished,

and means for vibrating said slurry such that said polishing particles are caused to have polishing movement against said exposed surface to be polished and thereby result in polishing thereof,

and means exerting a pressure on said polishing slurry while the same is confined in and in nonflowing relation to said chamber to provide intimate pressurized contact between said polishing slurry and said fixed exposed surface to be polished.

4. A surface polishing apparatus as defined in claim 3 wherein said pressure exerting means is variable and includes a cylinder having a supply of polishing slurry in fluid communication with said polishing chamber,

a piston operating in said cylinder effective to cause charging of said polishing slurry under pressure from said cylinder into said polishing chamber,

and means for maintaining said pressure of said polishing slurry during polishing operation of said surface polishing apparatus.

5. A surface polishing apparatus as defined in claim 4 including transducers operativcly arranged in said one of the walls bounding said polishing slurry chamber which is opposite said surface to be polished.

6. In the method of fine polishing a surface of an article utilizing a polishing slurry,

fixedly supporting the article whose surface is to be polished and exposing the surface to be polished by providing a spaced adjacent the surface,

confining the polishing slurry in and completely filling the space so that the slurry is in nonflowing, full surface contact with the surface to be polished and the defining walls of the space,

placing the confined nonflowing slurry under pressure to cause the slurry to contact the surface void free and under pressure,

and subjecting the slurry to ultrasonic vibrations to vibrate the same relative to the fixed article. 

1. An apparatus for polishing a surface of an article comprising a substantially closed chamber, means in said chamber to support an article in fixed position in said chamber exposing the surface of the article to be polished, a polishing slurry in said chamber, said slurry completely filling said chamber and being confined in nonflowing relation with the defines of said chamber and in polishing contact with the fixed surface to be polished, means connected with said chamber to place the polishing slurry therein under pressure to cause the polishing slurry to contact the fixed surface void free and under pressure, and means for vibrating the polishing slurry in said chamber to move the same relative to said fixed surface.
 2. A surface polishing apparatus as defined in claim 1 wherein said vibrating means are transducers located at least opposite said surface to be polished and with said polishing slurry therebetween to induce ultrasonic vibrations to said polishing slurry.
 3. A polishing apparatus for polishing the surface of an article comprising a polishing chamber including means therein to support the article with the surface thereof to be polished fixedly exposed in said chamber, a polishing slurry including polishing particles completely filling and confined in and in nonflowing relation with said chamber and in contact against said surface to be polished, and means for vibrating said slurry such that said polishing particles are caused to have polishing movement against said exposed surface to be polished and thereby result in polishing thereof, and means exerting a pressure on said polishing slurry while the same is confined in and in nonflowing relation to said chamber to provide intimate pressurized contact between said polishing slurry and said fixed exposed surface to be polished.
 4. A surface polishing apparatus as defined in claim 3 wherein said pressure exerting means is variable and includes a cylinder having a supply of polishing slurry in fluid communication with said polishing chamber, a piston operating in said cylinder effective to cause charging of said polishing slurry under pressure from said cylinder into said polishing chamber, and means for maintaining said pressure of said polishing slurry during polishing operation of said surface polishing apparatus.
 5. A surface polishing apparatus as defined in claim 4 including transducers operatively arranged in said one of the walls bounding said polishing slurry chamber which is opposite said surface to be polished.
 6. In the method of fine polishing a surface of an article utilizing a polishing slurry, fixedly supporting the article whose surface is to be polished and exposing the surface to be polished by providing a spaced adjacent the surface, confining the polishing slurry in and completely filling the space so that the slurry is in nonflowing, full surface contact with the surface to be polished and the defining walls of the space, placing the confined nonflowing slurry under pressure to cause the slurry to contact the surface void free and under pressure, and subjecting the slurry to ultrasonic vibrations to vibrate the same relative to the fixed article. 